1. Field
Exemplary embodiments of the invention relate to a liquid crystal display device, and more particularly to a liquid crystal display device, in which a common voltage is periodically varied.
2. Description of the Prior Art
A liquid crystal display device typically includes a liquid crystal layer having liquid crystal particles. In such a liquid crystal display device, as an electric field that is applied to a liquid crystal layer is changed, alignment of liquid crystal particles is changed, and light transmittance of the liquid crystal layer is changed based on the change of the alignment of the liquid crystal particles. When the light transmittance of the liquid crystal layer is controlled through adjustment of the strength of the electric field that is applied to the liquid crystal layer, an image corresponding to the electric field may be displayed.
A liquid crystal display device may include a common electrode and a pixel electrode to generate an electric field in a liquid crystal layer. The strength of the electric field applied to the liquid crystal layer may be varied corresponding to the electric potential difference between the common electrode and the pixel electrode. The common electrode may be commonly provided through a plurality of pixels to provide a common voltage to the plurality of pixels. The pixel electrode may be provided for each of the plurality of pixels, and a voltage corresponding to an image that is displayed on the liquid crystal display device may be applied to the pixel electrode. In such a liquid crystal display device, when the electric potential difference between the common electrode and the pixel electrode are constantly maintained in a same polarity for a long period of time, the performance of the liquid crystal layer may be deteriorated. Accordingly, the liquid crystal display device may be driven in a polarity inversion driving method that periodically inverts the polarity of the electric potential difference between the common electrode and the pixel electrode to effectively prevent such a performance deterioration of the liquid crystal layer.
In a liquid crystal display device, when the voltage of the pixel electrode higher than the voltage of the common electrode corresponds to “positive polarity” and a the voltage of the pixel electrode lower than the voltage of the common electrode corresponds to “negative polarity”, the common voltage that is applied to the common electrode may be continuously varied to reduce power consumption of the liquid crystal display device during the polarity inversion driving of the liquid crystal display device. For example, when the common voltage is changed to allow the common voltage of the positive polarity to become lower than the common voltage of the negative polarity, the difference between the maximum value of the voltage that may be applied to a pixel electrode in a positive polarity state and the minimum value of the voltage that may be applied to the pixel electrode in a negative polarity state may be reduced such that the range of the voltage that is applied to the pixel electrode may be decreased, and thus the power consumption of the liquid crystal display device may also be decreased.